A reach stacker is a loader which is suitable for the transferring of heavy loads such as containers, part loads and the like. The load handling with reach stackers does not take place via a lifting frame, but is rather carried out with the aid of a boom which is generally made as a telescopic boom. The present application is not restricted to reach stackers, but also includes other load units and/or lifting units such as stackers or other units which are suitable for load handling.
With such units usual today, the wheels are fully deflected on a maximum pre-setting of the steering angle.
Since the maximum steering movement, i.e. the total steering range, is also available at high speeds, depending on the combination of speed and steering movement, situations can arise in which the potential for the unit to overturn may be increased. For example, the standing stability, or standing safety, may be decreased. With units usual today, it is exclusively at the discretion of the driver which steering movement is to be selected to avoid a tilting of the unit or not to move into a critical driving situation.
It is the underlying object of the present application to further develop a loading unit and/or lifting unit, and in particular a reach stacker, such that critical driving situations can be recognized and reduced or avoided.
This object is satisfied by a loading or lifting unit, in particular a reach stacker with one or more pick-ups for the detection of at least one operating parameter influencing the standing safety or stability of the unit and a computing unit in communication with the pick-ups which has means by means of which a maximum permitted value of an operating parameter for the ensuring of the standing safety is determined in dependence on one or more of the operating parameters detected. The term “operating parameter” is to be understood widely and includes, for example, at least one of the driving speed or the steering movement, the lifting load, the load height, the inclination and the working radius of the loading unit and/or lifting unit, or combinations thereof.
The calculation unit in accordance with one embodiment has means or a logic by means of which a maximum permitted value of a parameter, for example the steering movement, is determined from the measured parameter(s). The maximum permitted value of a parameter is determined with respect to the fact that the standing safety of the unit remains ensured or improved.
It is, for example, feasible that it is determined in a driving situation at a specific speed in which range of the steering movement the standing safety is given. A maximum permitted steering movement is determined on this basis. It is furthermore feasible, for example, that in a driving situation with a specific steering movement, it is determined up to which speed range the standing safety is given, i.e. up to which value the speed can be increased.
It is advantageous if not only one operating parameter is taken into the calculation, but a plurality or all parameters which have an influence on the standing safety of the unit are considered. However, in one embodiment, only a single parameter may be used.
In one embodiment, the operating parameter whose maximum value is determined is the steering movement of the loading unit and/or lifting unit.
The calculation unit can be made such that it determines the maximum permitted value of a parameter, for example of the steering movement, on the basis of only one operating parameter or advantageously on the basis of a plurality of operating parameters or all operating parameters. A critical driving situation can be reliably avoided if all parameters which have an influence on the standing safety of the unit go into the calculation of the maximum permitted steering movement. Examples for such parameters are the driving speed, the lifting load, the working radius, the load height, the boom inclination and the ground gradient or the inclination of the unit, or combinations thereof. Other characteristic values or parameters can also be of importance and be included in the calculation. The calculation unit or the logic contained therein determines the maximum permitted value of a parameter or of the steering movement at which the standing safety is still ensured on the basis of a known dependence of the standing safety of the unit on the parameters which influence it.
In another aspect, a pick-up is provided for the detection of the actual steering movement. This transducer can be made in a redundant manner, if desired.
In a further aspect, comparison means are provided by means of which the actual steering movement is compared with the maximum permitted steering movement. The actual steering movement is determined by one or more pick-ups and compared with the permitted steering movement. The comparison means provided for this purpose can be a component of the calculating unit. The comparison result can be used, for example, to inform the operator that an exceeding of the maximum permitted steering movement is present. Such a signal can be reproduced acoustically or visually, for example.
Furthermore, an embodiment is feasible in which an exceeding of a maximum permitted parameter value is generally precluded.
In accordance with a further embodiment, means are provided by means of which—on the changing of an operating parameter, for example on an increase of the speed which would result in an exceeding of the maximum permitted value of a parameter, for example the steering angle—another operating parameter is changed such that the actual value does not exceed the maximum permitted value.
If, for example, the lifting height or the working radius is increased such that with otherwise unchanged further operating parameters and with an unchanged steering movement, an exceeding of the maximum permitted steering movement and thus a critical driving situation would result, in accordance with this embodiment another parameter, for example the driving speed, is changed—reduced in this example—so that an exceeding of the maximum permitted steering movement does not occur and the standing safety remains ensured.
If, for example, the steering movement is increased beyond the maximum permitted steering movement, provision can be made in accordance with this embodiment for another operating parameter, for example the working radius or the travel speed, to be changed, i.e. reduced, such that the permitted range of the steering movement covers the actual steering movement.
If, in a further example of this embodiment, the speed of e.g. the reach stacker is increased such that, with otherwise unchanged operating parameters and steering movement, a critical situation would arise, provision is made for another parameter, for example the working radius or the lifting height, to be reduced in the degree by which the speed is increased such that no exceeding of the maximum permitted steering movement occurs.
Which parameter is changed for the aforesaid purpose can be fixedly pre-set or be selectable.
Provision can be made in a further embodiment for means to be provided which have the effect that a change of an operating parameter is only possible to the extent in which the maximum permitted value of a parameter is not exceeded with otherwise unchanged operating parameters. In this case, a critical driving situation can also be avoided. A difference from the aforesaid embodiment results in that a compensation by another parameter does not take place.
Accordingly, means can be provided which have the effect that a change of an operating parameter is only possible to that extent in which, for example, the permitted range of the steering movement is not exceeded (without changing other parameters). In this case, for example, the lifting height or the working radius can only be changed to that extent—with otherwise unchanged operating parameters—that the actual steering movement remains in the permitted range.
If, in this embodiment, a reach stacker is, for example, accelerated, the other operating parameters are not changed and the speed increase is only possible to the extent that the standing safety of the reach stacker is still ensured, i.e. that the actual steering movement coincides with the permitted steering movement.
As stated above, means can be provided for the display of the maximum permitted steering movement and/or for the emission of a signal when the actual value, for example, the steering movement, exceeds the maximum permitted value.
Provision can be made in a further aspect for the calculation unit furthermore to have means by means of which an optimum steering speed or steering acceleration can be determined in dependence on one or more of the operating parameters detected. The operating parameters detected can be parameters which are used for the determination of the permitted range of a parameter. Means are preferably provided for the setting of the actual steering speed to the determined optimum steering speed. In this manner, the steering speed and the steering acceleration can be changed in accordance with the driving situation in order to ensure the standing safety of the unit. It is thus feasible that, for example, an increase of the driving speed does not only result in a reduction in the permitted range of the steering movement, but also in a reduction in the steering speed and steering acceleration.
In a further aspect, means are provided by means of which the maximum permitted steering movement is set at a maximum pre-setting of the steering angle. Accordingly, with a maximum pre-setting of the steering angle, the wheels are not necessarily moved fully, but only up to the maximum permitted steering movement.
Further details and advantages will be explained with reference to an embodiment shown in the drawing.